Prevent unauthorized visitors from gaining entry to your home or business. This electromagnetic lock (mag-lock) was designed specifically to keep double-doors securely closed. It has 1,200 pounds of holding force, when power is applied to the magnetic lock it turns on the unit's powerful built-in electromagnet. The lock can be triggered by your security system, relay switch, or even with a standalone RF transmitter and receiver system (each sold separately). The built-in Bond Sensor and dual-color LED show the lock status - Green: Door is closed and locked, Red: Door not closed and / or locked, off: Door in use / no power.